Radish black rot, commonly known as black heart and rotten heart, is a disease caused by bacteria. When the leaf is infected, the leaf margin is V-shaped, the veins turn black, the leaf margin turns yellow, and then it spreads to the whole leaf. The infected root canal turns black, the internal tissue is dry and rotten, and there are often no obvious symptoms in appearance, but the pith is mostly black and dry, thus forming cavities. Soft rot often occurs in the field and eventually rots.

1. Pathogenic conditions: suitable temperature is 25-30℃, high temperature and rainy, continuous cropping or early sowing, low terrain, excessive irrigation, poor drainage, little or no chemical fertilizer application, and frequent human injuries and insect injuries.

2. Prevention and control methods: Take prevention first and comprehensive prevention and control methods.

(1) rotation, using formula fertilization technology.

(2) sow in time, not too early.

(3) Select disease-resistant varieties, such as Feng Guang First Generation Radish, Qiao Hong 1, Shijiazhuang White Radish, etc.

(4) seed treatment. Soak in warm water at 50℃ for 30 minutes, or dry-heat sterilize at 60℃ for 6 hours, or seed dressing with 50% thiram wettable powder accounting for 0.2% of the seed weight.

(5) Soil treatment. Before sowing, apply 750g of 40% quintozene powder per acre. The method is to take 750g of this bactericide, add water10l, mix it with100kg of fine soil, and scatter it in the hole. (6) Strengthen field management, irrigate with small amount of water at seedling stage, reduce ground temperature, and interplant seedlings in time.

(7) Spraying 3000-4000 times of 72% agricultural streptomycin sulfate soluble powder, 700 times of 47% Jialenong wettable powder or 300 times of 14% copper chloride aqueous solution at the initial stage of the disease, and spraying 1 time every 7- 10 days for 3-4 times continuously.